1. Field of the Invention
The present invention relates to a time-division multiple access (TDMA) radio communication device that automatically can generate acknowledgement data and send the data for response. The present invention relates also to a time-division multiple access radio communication system using the device.
2. Description of the Prior Art
In recent years, various portable communication devices using time-division multiple access radio communication system have been developed. For the portability and durability, the devices are required to be smaller and to minimize power consumption.
An acknowledgement method for a conventional time-division multiple access radio communication system includes the following steps of:
storing received data in a receive-data buffer, based on a synchronization information at a unique word detecting portion;
carrying out CRC calculation by processing with software using a microprocessor; and
writing the results in a send-data buffer for sending.
An acknowledgement method in such a conventional time-division multiple access radio communication system is described below by referring to FIG. 4. In FIG. 4, numeral 401 denotes an antenna for receiving data, and 402 denotes a unique word detecting portion. Numeral 403 denotes a receive-data buffer portion, 404 denotes a microprocessor portion, and 405 denotes a send-data buffer portion. Numeral 406 denotes an antenna for sending data, 411 denotes a receive-data processing path, 412 denotes a unique word detection signal, and 413 denotes a send-data processing path.
In FIG. 4, received data inputted from the antenna 401 is passed over the receive-data processing path 411 into the unique word detecting portion 402 and also the receive-data buffer portion 403. When the unique word detecting portion 402 detects a unique word in the received data, it gives out the unique word detection signal 412 and notifies the microprocessor portion 404.
In the microprocessor portion 404, the unique word detection signal 412 is inputted and waits for a certain period until the received data are completely stored in the receive-data buffer portion 403, so that the timing to start the cyclic redundancy check (CRC) calculation is adjusted. A remainder term as a result of division for checking transmission errors is added to the received data.
When the received data are completely stored in the receive-data buffer portion 403, CRC calculation is carried out for obtaining the remainder term by the above-mentioned division based on the received data. If the remainder term obtained by the CRC calculation coincides with a remainder term (CRC) sent together with the received data, the received data are regarded as error-free, and acknowledgement send data are prepared in the send-data buffer portion 405 for acknowledgement. And the microprocessor portion 404 directs sending in accordance with timing of sending data at the certain station. Consequently, acknowledgement data are sent to the antenna 406 through the send-data processing path 413, and the data are outputted as a radio wave.
However, in some time-division multiple access radio communication systems, acknowledgement should be sent immediately in accordance with the timing of the desired station. In such a case, a CPU is kept busy with the acknowledgement process or the CPU is unduly loaded if acknowledgment is carried out by the conventional software processing. And thus, it prevents other processes from being carried out on the CPU. To solve such a problem, acknowledgement is often processed with a high-speed microprocessor specialized for an acknowledgement process. However, it will cause some problems, e.g., the communication device consumes much power, or the component cost rises.
Such a conventional system uses a send-data buffer designed for normal communication. Therefore, the normal send-data should be moved to and kept in another memory during acknowledgement. This also causes problems, for example, the component cost rises and communication response deteriorates due to replacement of data.
It is an object of the present invention to solve these problems by using memories or the like exclusive to acknowledgement, so that power consumption is lowered, component cost is reduced and speed of response is improved.
In order to achieve the object, a time-division multiple access radio communication device according to this invention comprises:
a receive-data buffer portion to receive data from plural sources by sing a carrier wave and store the received data;
a unique word detecting portion to detect a unique word from the received data to determine a synchronous point as a starting point for timing adjustment;
a timer portion for the timing adjustment by counting time from the point that the unique word is detected at the unique word detecting portion;
a CRC calculating portion to check errors in the received data; and
a send-data buffer portion to store the data to be sent. The time-division multiple access radio communication device is further provided with an acknowledgement data generating portion. This acknowledgement data generating portion checks errors in the received data based on a calculation result at the CRC calculating portion in accordance with the timing counted at the timer portion. When the received data are assumed to be error-free, the acknowledgement data generating portion generates acknowledgement data and stores the data in a storage region distinguished from the send-data buffer portion.
As a result, acknowledgement data can be sent without providing a high-speed microprocessor exclusive to acknowledgement. In addition, since the acknowledgement data are stored in a storage region distinguished from the send-data buffer portion, the acknowledgement data are not replaced by normal send-data at a send-data buffer. Thus, deterioration of the communication response can be prevented.
The time-division multiple access radio communication device preferably includes plural receive-data buffers at a receive-data buffer portion, and includes plural send-data buffers at a send-data buffer portion. If the device includes plural data buffers for receiving and sending data respectively, send-/receive-data are not replaced at the send-/receive-data buffers even when plural data are sent/received simultaneously, and consequently, deterioration of the communication response can be prevented.
A time-division multiple access radio communication method according to the present invention includes the following steps of:
receiving data from plural sources by using a carrier wave and storing the data;
detecting a unique word from the received data in order to determine a synchronous point as a starting point for timing adjustment;
counting time from the point that the unique word is detected;
carrying out CRC calculation for checking errors in the received data; and
storing the data to be sent. The method further includes the steps of:
checking errors in the received data based on the CRC calculation result;
generating acknowledgement data when the received data are assumed to be error-free; and
storing the acknowledgement data in a storage region distinguished from the send-data buffer portion.
As a result, acknowledgement data can be sent without providing a high-speed microprocessor exclusive to acknowledgment. In addition, since the acknowledgement data are stored in a storage region distinguished from the send-data buffer portion, the acknowledgement data are not replaced by normal send-data at a send-data buffer. And thus, deterioration of the communication response can be prevented.